1. Field of the Invention
The present invention relates to a transformer, and more particularly to a split-winding pulse transformer.
2. Description of the Related Art
A conventional split-winding pulse transformer from which a variety of outputs for use in a video taper recorder can be obtained will now be described with reference to FIGS. 9(A) and 9(B).
FIG. 9(A) is a front view showing a conventional split-winding pulse transformer and FIG. 9(B) is a rear view of the same.
The conventional split-winding pulse transformer includes a core portion 10 disposed vertically, a terminal frame 20 for holding the lower portion of the core portion 10, a plurality of primary-terminal portions 30 and a plurality of secondary-terminal portions 31 provided below the terminal frame 20 in a dual in-line configuration, a bobbin portion 11 received by a core member of the core portion 10, and a base winding 12, primary windings 13 and 15 and secondary windings 14 wound around the bobbin portion 11.
In order to generate a plurality of voltage levels (four voltage levels in FIGS. 9(A) and 9(B)) required in a video tape recorder, the conventional split-winding pulse transformer has a structure in which four types of secondary windings 14 are wound around the bobbin portion 11 in a stacked manner. The four types of secondary windings 14 are wired to reach the secondary-terminal portions 31 across the primary winding 13, the base winding 12 and the terminal frame 20 which are disposed below the secondary windings 14.
The base winding 12 is wired to reach the primary-terminal portions 30 across the terminal frame 20.
The primary winding 13 is wired to reach the primary-terminal portions 30 across the base winding 12 and the terminal frame 20.
The other primary winding 15 is wired to reach the primary-terminal portions 30 across the secondary windings 14, the base winding 12, the primary winding 13 and the terminal frame 20.
However, the conventional split-winding pulse transformer requires wiring from each winding to predetermined terminal portions 30 (or 31) across the other windings and the terminal frame 20. Therefore, the wiring after winding and arrangement of the wires are too complicated to realize satisfactory workability. What is worse, design of the wiring requires a long time and excess wiring must be performed. In addition, there is apprehension that the wire is damaged when the wiring operation is performed.
On the other hand, a transformer has been disclosed in Japanese Utility Model Examined Publication No. Sho. 36-24294, the transformer being arranged in a manner that the central axes of windings are positioned horizontally with respect to a printed circuit board. The transformer has a plurality of projecting terminal portions each of which is formed at the lower end portion of two side walls of a bobbin around which the windings are wound. Moreover, the leading ends of the windings are connected to the terminal portions. Mounting of the transformer on the printed circuit board is performed by inserting the terminal portions into cut holes formed in the printed circuit board and by dipping it into a soldering dip vat.
Although such a transformer may be able to overcome the above-described problems, it is not a split-winding transformer. Moreover, strength for mounting the transformer on the printed circuit board is unsatisfactory.